From: Mikael Djurfeldt <mdj@kvast.blakulla.net>
Cc: djurfeldt@nada.kth.se
Subject: [pthreads] performance test using fib.scm
Date: Tue, 10 Dec 2002 19:16:04 +0100 [thread overview]
Message-ID: <E18LovM-0003lg-00@kvast.blakulla.net> (raw)
In the announcement of the pthreads support, I attached a program
fib.scm:
(define (par-fib n n-forks)
(cond ((<= n 1) 1)
((> n-forks 0)
(letpar ((f1 (par-fib (- n 1) (- n-forks 1)))
(f2 (par-fib (- n 2) (- n-forks 1))))
(+ f1 f2)))
(else
(let ((f1 (mono-fib (- n 1)))
(f2 (mono-fib (- n 2))))
(+ f1 f2)))))
(define (mono-fib n)
(let iter ((f1 1) (f2 1) (i 1))
(if (>= i n)
f2
(iter f2 (+ f1 f2) (+ 1 i)))))
When I run this with a Guile compiled with COPT threads, it invariably
takes around 12 s to run (par-fib 40000 1) on my dual CPU machine.
"Top" reports 50% of CPU capacity usage during calculation.
With the new pthreads support (which now allows for real SMP), it
takes 2.6 s and top says 91%!
Still, for large fibonnaci numbers and large branch depths (many
threads), Guile often crashes in realloc. That function should be
thread safe, shouldn't it? Maybe we're trashing up the heap somewhere
else...
Anyone keen on some debugging? :-)
Mikael
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next reply other threads:[~2002-12-10 18:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-10 18:16 Mikael Djurfeldt [this message]
2002-12-10 21:10 ` [pthreads] performance test using fib.scm Wolfgang Jaehrling
2002-12-10 20:10 ` Mikael Djurfeldt
2002-12-11 20:05 ` Christopher Cramer
2002-12-11 5:02 ` Maciej Stachowiak
2002-12-11 7:11 ` Mikael Djurfeldt
2002-12-11 13:48 ` Maciej Stachowiak
2002-12-11 23:43 ` Han-Wen Nienhuys
2002-12-11 16:59 ` Wolfgang Jaehrling
[not found] ` <200212110202.gBB22Et27423@mule.m17n.org>
2002-12-11 17:27 ` Wolfgang Jaehrling
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